msem-instigator

Flying
When Mei's Understudy enters, if you control another Actor, draw a card.

Whenever Merfolk Vandal deals combat damage to a player, you may pay {U}. If you do, transform it.

Whenever Shoreline Stormers deals damage to a player, draw a card.
{2}{U}: Target creature can't be blocked this turn.

Counter target spell.

Flying
When Moonlit Charmer enters, tap target artifact or creature. It doesn't untap during its controller's next untap step.

{U}, {T}: Sacrifice any number of nontoken creatures. Create an X/X blue Horror creature token, where X is the total power of those creatures. Then if X is 4 or greater, you may transform Performer of Brilliance.

At the beginning of your end step, if you have no cards in hand, draw a card.
{2}{U}, {T}: Sacrifice any number of nontoken creatures. Create an X/X blue Horror creature token for each of those creatures, where X is the total power of those creatures.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II — Target opponent mills three cards.
III — You may cast target nonland card from a graveyard this turn and you may spend blue mana as though it were mana of any color to cast it.

When Posthumous Informant dies, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

At the beginning of combat on your turn, whenever target creature deals combat damage to a player this turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

When Queue Bouncer enters, return target creature to its owner's hand. If you control another Actor, instead put that creature on top of its owner's library.

(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
Your opponents play with their hands revealed.
I, II — Return target nonland permanent an opponent controls to its owner's hand.
III — Gain control of target nonland permanent.

When Saia's Protege enters, gain control of target artifact or enchantment for as long as you control Saia's Protege.

Return target non-Horror creature to its owner's hand. Scry 1.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Marked creatures your opponents control lose all abilities.

Enchant creature or enchantment
Enchanted permanent doesn't untap during its controller's untap step.
Enchanted permanent can't have counters put on it.

Whenever you cast a spell during an opponent's turn, investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Whenever you sacrifice a Clue, Vivian's Vanguard gets +2/+0 and gains flying until end of turn.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Alley Hunter has lifelink as long as it's blocked by a marked creature.

When Arisen Troops dies, you may destroy target creature that was dealt damage this turn.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Whenever Backalley Silencer deals combat damage to a player, destroy target marked creature.

Draw a card for each creature that died this turn.

Bloodline Zealot gets +2/+0 and has menace as long as you've sacrificed a permanent this turn.

Enchant creature
Enchanted creature gets +2/+2 as long as it's an Actor. Otherwise, it gets -2/-2.